1. Field of the Invention
The invention is in the field of fabrication of ferromagnetic ceramic devices, primarily for incorporation in electronic circuits.
2. Brief Description of the Background Art
Ferrite toroids are used in electronic circuits as inductors and transformers. Some applications require toroids in which the magnetic path is interrupted by a non-magnetic gap. Gapped ferrite toroids are currently manufactured by cutting a single gap in a toroid using a diamond blade or some other cutting method, as shown in FIG. 1. Alternatively, very elaborate machining methods may be used to produce double gapped toroids. This latter procedure may involve the cementing of blocks of ferrite together, separated by a spacer which joins the two blocks. Gapped toroids are produced by core drilling toroids from the bonded blocks, with the core drill centered on the gap between the blocks. This method is shown in FIG. 2.
Several other kinds of magnetic devices are fabricated from a combination of magnetic ferrite elements and nonmagnetic spacers. For example, the fabrication of reading and writing heads for magnetic tape and magnetic disc recording is shown in U.S. Pat. No. 4,045,864 and U.S. Pat. No. 4,182,643. U.S. Pat. No. 5,655,287 discloses multilayer nonmagnetic ceramic green sheets with printed metalic conductors compressed to form a coil and surrounded by magnetic green sheets to form the magnetic circuit and fired to form a monolithic body. U.S. Pat. No. 5,479,695 discloses similarly layered and co-fired magnetic and nonmagnetic ceramics electronic components. U.S. Pat. No. 3,535,200 discloses a high coercive force permanent magnet consisting of alternating layers of ceramic ferrites with different magnetic properties compressed and fired together.